How to execute an Sparql query in android using androjena 0.5

-1

I'm trying to execute a simple Sparql query from my android device. The online endpoint that I am using is https://dbpedia.org/sparql with URI http://dbpedia.org and the query:

"select distinct ?Concept where { a ?Concept} LIMIT 100".

I successfully imported to my Android project the libraries of androjena 0.5 and arqoid 0.5. Studing the code from this helpful tutorial I changed some lines and I ended up with the following code:

import java.util.List;

import com.hp.hpl.jena.query.Query;

import com.hp.hpl.jena.query.QueryExecution;

import com.hp.hpl.jena.query.QueryExecutionFactory;

import com.hp.hpl.jena.query.QueryFactory;

import com.hp.hpl.jena.query.QuerySolution;

import com.hp.hpl.jena.query.ResultSet;

import com.hp.hpl.jena.query.Syntax;



public class SparqlExamples {

    public String queryRemoteSparqlEndpoint() {



        String queryString = "select distinct ?Concept where { a ?Concept} LIMIT 100";

        String sparqlEndpointUri = "https://dbpedia.org";

        Query query = QueryFactory.create(queryString, Syntax.syntaxARQ);

        query.setLimit(10);

        query.setOffset(1);

        QueryExecution qe = QueryExecutionFactory.sparqlService(sparqlEndpointUri, query);

        ResultSet resultSet = qe.execSelect();

        StringBuffer results = new StringBuffer();

        List<String> columnNames = resultSet.getResultVars();

        while (resultSet.hasNext()) {

            QuerySolution solution = resultSet.next();

            for (String var : columnNames) {

                results.append(var + ": ");

                if (solution.get(var) == null) {

                    results.append("{null}");

                } else if (solution.get(var).isLiteral()) {

                    results.append(solution.getLiteral(var).toString());

                } else {

                    results.append(solution.getResource(var).getURI());

                }

                results.append('n');

            }

            results.append("-----------------n");

        }

        qe.close();

        return results.toString();

    }

}

and the MainActivity:

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;



public class MainActivity extends AppCompatActivity {



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);



        String results = new SparqlExamples().queryRemoteSparqlEndpoint();

        Log.d("results","results"+String.valueOf(results));

    }

}

I will appreciate any idea that could help in this issue.

edited Nov 21 '18 at 14:30

TallTed

6,14321527

asked Nov 20 '18 at 21:15

A Damian

1

What's the specific problem

– fedache
Nov 20 '18 at 21:31

Next time, provide the error message you receive... stackoverflow.com/help/how-to-ask

– TallTed
Nov 20 '18 at 23:05

The specific problem is that I do not receive any response from server and the app crashes after installation. LogCat shows that the problem begins in this command: ResultSet resultSet = qe.execSelect();

– A Damian
Nov 21 '18 at 9:20

Please edit your question to include the "specific problem" details. Note that the sparqlEndpointUri for DBpedia is https://dbpedia.org/sparql (not https://dbpedia.org), and this must be reflected in your code.

– TallTed
Nov 21 '18 at 14:31

If there's a crash, there's usually a crash stacktrace you should include here. If I'd have to guess, it's NetworkOnMainThreadException. You need to offload network calls to a background thread.

– laalto
Nov 21 '18 at 14:32

|
show 1 more comment

-1

I'm trying to execute a simple Sparql query from my android device. The online endpoint that I am using is https://dbpedia.org/sparql with URI http://dbpedia.org and the query:

"select distinct ?Concept where { a ?Concept} LIMIT 100".

I successfully imported to my Android project the libraries of androjena 0.5 and arqoid 0.5. Studing the code from this helpful tutorial I changed some lines and I ended up with the following code:

import java.util.List;

import com.hp.hpl.jena.query.Query;

import com.hp.hpl.jena.query.QueryExecution;

import com.hp.hpl.jena.query.QueryExecutionFactory;

import com.hp.hpl.jena.query.QueryFactory;

import com.hp.hpl.jena.query.QuerySolution;

import com.hp.hpl.jena.query.ResultSet;

import com.hp.hpl.jena.query.Syntax;



public class SparqlExamples {

    public String queryRemoteSparqlEndpoint() {



        String queryString = "select distinct ?Concept where { a ?Concept} LIMIT 100";

        String sparqlEndpointUri = "https://dbpedia.org";

        Query query = QueryFactory.create(queryString, Syntax.syntaxARQ);

        query.setLimit(10);

        query.setOffset(1);

        QueryExecution qe = QueryExecutionFactory.sparqlService(sparqlEndpointUri, query);

        ResultSet resultSet = qe.execSelect();

        StringBuffer results = new StringBuffer();

        List<String> columnNames = resultSet.getResultVars();

        while (resultSet.hasNext()) {

            QuerySolution solution = resultSet.next();

            for (String var : columnNames) {

                results.append(var + ": ");

                if (solution.get(var) == null) {

                    results.append("{null}");

                } else if (solution.get(var).isLiteral()) {

                    results.append(solution.getLiteral(var).toString());

                } else {

                    results.append(solution.getResource(var).getURI());

                }

                results.append('n');

            }

            results.append("-----------------n");

        }

        qe.close();

        return results.toString();

    }

}

and the MainActivity:

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;



public class MainActivity extends AppCompatActivity {



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);



        String results = new SparqlExamples().queryRemoteSparqlEndpoint();

        Log.d("results","results"+String.valueOf(results));

    }

}

I will appreciate any idea that could help in this issue.

edited Nov 21 '18 at 14:30

TallTed

6,14321527

asked Nov 20 '18 at 21:15

A Damian

1

What's the specific problem

– fedache
Nov 20 '18 at 21:31

Next time, provide the error message you receive... stackoverflow.com/help/how-to-ask

– TallTed
Nov 20 '18 at 23:05

The specific problem is that I do not receive any response from server and the app crashes after installation. LogCat shows that the problem begins in this command: ResultSet resultSet = qe.execSelect();

– A Damian
Nov 21 '18 at 9:20

Please edit your question to include the "specific problem" details. Note that the sparqlEndpointUri for DBpedia is https://dbpedia.org/sparql (not https://dbpedia.org), and this must be reflected in your code.

– TallTed
Nov 21 '18 at 14:31

If there's a crash, there's usually a crash stacktrace you should include here. If I'd have to guess, it's NetworkOnMainThreadException. You need to offload network calls to a background thread.

– laalto
Nov 21 '18 at 14:32

|
show 1 more comment

-1

I'm trying to execute a simple Sparql query from my android device. The online endpoint that I am using is https://dbpedia.org/sparql with URI http://dbpedia.org and the query:

"select distinct ?Concept where { a ?Concept} LIMIT 100".

I successfully imported to my Android project the libraries of androjena 0.5 and arqoid 0.5. Studing the code from this helpful tutorial I changed some lines and I ended up with the following code:

import java.util.List;

import com.hp.hpl.jena.query.Query;

import com.hp.hpl.jena.query.QueryExecution;

import com.hp.hpl.jena.query.QueryExecutionFactory;

import com.hp.hpl.jena.query.QueryFactory;

import com.hp.hpl.jena.query.QuerySolution;

import com.hp.hpl.jena.query.ResultSet;

import com.hp.hpl.jena.query.Syntax;



public class SparqlExamples {

    public String queryRemoteSparqlEndpoint() {



        String queryString = "select distinct ?Concept where { a ?Concept} LIMIT 100";

        String sparqlEndpointUri = "https://dbpedia.org";

        Query query = QueryFactory.create(queryString, Syntax.syntaxARQ);

        query.setLimit(10);

        query.setOffset(1);

        QueryExecution qe = QueryExecutionFactory.sparqlService(sparqlEndpointUri, query);

        ResultSet resultSet = qe.execSelect();

        StringBuffer results = new StringBuffer();

        List<String> columnNames = resultSet.getResultVars();

        while (resultSet.hasNext()) {

            QuerySolution solution = resultSet.next();

            for (String var : columnNames) {

                results.append(var + ": ");

                if (solution.get(var) == null) {

                    results.append("{null}");

                } else if (solution.get(var).isLiteral()) {

                    results.append(solution.getLiteral(var).toString());

                } else {

                    results.append(solution.getResource(var).getURI());

                }

                results.append('n');

            }

            results.append("-----------------n");

        }

        qe.close();

        return results.toString();

    }

}

and the MainActivity:

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;



public class MainActivity extends AppCompatActivity {



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);



        String results = new SparqlExamples().queryRemoteSparqlEndpoint();

        Log.d("results","results"+String.valueOf(results));

    }

}

I will appreciate any idea that could help in this issue.

edited Nov 21 '18 at 14:30

TallTed

6,14321527

asked Nov 20 '18 at 21:15

A Damian

I'm trying to execute a simple Sparql query from my android device. The online endpoint that I am using is https://dbpedia.org/sparql with URI http://dbpedia.org and the query:

"select distinct ?Concept where { a ?Concept} LIMIT 100".

I successfully imported to my Android project the libraries of androjena 0.5 and arqoid 0.5. Studing the code from this helpful tutorial I changed some lines and I ended up with the following code:

import java.util.List;

import com.hp.hpl.jena.query.Query;

import com.hp.hpl.jena.query.QueryExecution;

import com.hp.hpl.jena.query.QueryExecutionFactory;

import com.hp.hpl.jena.query.QueryFactory;

import com.hp.hpl.jena.query.QuerySolution;

import com.hp.hpl.jena.query.ResultSet;

import com.hp.hpl.jena.query.Syntax;



public class SparqlExamples {

    public String queryRemoteSparqlEndpoint() {



        String queryString = "select distinct ?Concept where { a ?Concept} LIMIT 100";

        String sparqlEndpointUri = "https://dbpedia.org";

        Query query = QueryFactory.create(queryString, Syntax.syntaxARQ);

        query.setLimit(10);

        query.setOffset(1);

        QueryExecution qe = QueryExecutionFactory.sparqlService(sparqlEndpointUri, query);

        ResultSet resultSet = qe.execSelect();

        StringBuffer results = new StringBuffer();

        List<String> columnNames = resultSet.getResultVars();

        while (resultSet.hasNext()) {

            QuerySolution solution = resultSet.next();

            for (String var : columnNames) {

                results.append(var + ": ");

                if (solution.get(var) == null) {

                    results.append("{null}");

                } else if (solution.get(var).isLiteral()) {

                    results.append(solution.getLiteral(var).toString());

                } else {

                    results.append(solution.getResource(var).getURI());

                }

                results.append('n');

            }

            results.append("-----------------n");

        }

        qe.close();

        return results.toString();

    }

}

and the MainActivity:

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;



public class MainActivity extends AppCompatActivity {



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);



        String results = new SparqlExamples().queryRemoteSparqlEndpoint();

        Log.d("results","results"+String.valueOf(results));

    }

}

I will appreciate any idea that could help in this issue.

import java.util.List;

import com.hp.hpl.jena.query.Query;

import com.hp.hpl.jena.query.QueryExecution;

import com.hp.hpl.jena.query.QueryExecutionFactory;

import com.hp.hpl.jena.query.QueryFactory;

import com.hp.hpl.jena.query.QuerySolution;

import com.hp.hpl.jena.query.ResultSet;

import com.hp.hpl.jena.query.Syntax;



public class SparqlExamples {

    public String queryRemoteSparqlEndpoint() {



        String queryString = "select distinct ?Concept where { a ?Concept} LIMIT 100";

        String sparqlEndpointUri = "https://dbpedia.org";

        Query query = QueryFactory.create(queryString, Syntax.syntaxARQ);

        query.setLimit(10);

        query.setOffset(1);

        QueryExecution qe = QueryExecutionFactory.sparqlService(sparqlEndpointUri, query);

        ResultSet resultSet = qe.execSelect();

        StringBuffer results = new StringBuffer();

        List<String> columnNames = resultSet.getResultVars();

        while (resultSet.hasNext()) {

            QuerySolution solution = resultSet.next();

            for (String var : columnNames) {

                results.append(var + ": ");

                if (solution.get(var) == null) {

                    results.append("{null}");

                } else if (solution.get(var).isLiteral()) {

                    results.append(solution.getLiteral(var).toString());

                } else {

                    results.append(solution.getResource(var).getURI());

                }

                results.append('n');

            }

            results.append("-----------------n");

        }

        qe.close();

        return results.toString();

    }

}

import java.util.List;

import com.hp.hpl.jena.query.Query;

import com.hp.hpl.jena.query.QueryExecution;

import com.hp.hpl.jena.query.QueryExecutionFactory;

import com.hp.hpl.jena.query.QueryFactory;

import com.hp.hpl.jena.query.QuerySolution;

import com.hp.hpl.jena.query.ResultSet;

import com.hp.hpl.jena.query.Syntax;



public class SparqlExamples {

    public String queryRemoteSparqlEndpoint() {



        String queryString = "select distinct ?Concept where { a ?Concept} LIMIT 100";

        String sparqlEndpointUri = "https://dbpedia.org";

        Query query = QueryFactory.create(queryString, Syntax.syntaxARQ);

        query.setLimit(10);

        query.setOffset(1);

        QueryExecution qe = QueryExecutionFactory.sparqlService(sparqlEndpointUri, query);

        ResultSet resultSet = qe.execSelect();

        StringBuffer results = new StringBuffer();

        List<String> columnNames = resultSet.getResultVars();

        while (resultSet.hasNext()) {

            QuerySolution solution = resultSet.next();

            for (String var : columnNames) {

                results.append(var + ": ");

                if (solution.get(var) == null) {

                    results.append("{null}");

                } else if (solution.get(var).isLiteral()) {

                    results.append(solution.getLiteral(var).toString());

                } else {

                    results.append(solution.getResource(var).getURI());

                }

                results.append('n');

            }

            results.append("-----------------n");

        }

        qe.close();

        return results.toString();

    }

}

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;



public class MainActivity extends AppCompatActivity {



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);



        String results = new SparqlExamples().queryRemoteSparqlEndpoint();

        Log.d("results","results"+String.valueOf(results));

    }

}

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;



public class MainActivity extends AppCompatActivity {



    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);



        String results = new SparqlExamples().queryRemoteSparqlEndpoint();

        Log.d("results","results"+String.valueOf(results));

    }

}

android sparql jena

edited Nov 21 '18 at 14:30

TallTed

6,14321527

asked Nov 20 '18 at 21:15

A Damian

edited Nov 21 '18 at 14:30

TallTed

6,14321527

asked Nov 20 '18 at 21:15

A Damian

edited Nov 21 '18 at 14:30

TallTed

6,14321527

edited Nov 21 '18 at 14:30

TallTed

6,14321527

edited Nov 21 '18 at 14:30

TallTed

6,14321527

asked Nov 20 '18 at 21:15

A Damian

asked Nov 20 '18 at 21:15

A Damian

asked Nov 20 '18 at 21:15

A Damian

1

What's the specific problem

– fedache
Nov 20 '18 at 21:31

Next time, provide the error message you receive... stackoverflow.com/help/how-to-ask

– TallTed
Nov 20 '18 at 23:05

The specific problem is that I do not receive any response from server and the app crashes after installation. LogCat shows that the problem begins in this command: ResultSet resultSet = qe.execSelect();

– A Damian
Nov 21 '18 at 9:20

Please edit your question to include the "specific problem" details. Note that the sparqlEndpointUri for DBpedia is https://dbpedia.org/sparql (not https://dbpedia.org), and this must be reflected in your code.

– TallTed
Nov 21 '18 at 14:31

If there's a crash, there's usually a crash stacktrace you should include here. If I'd have to guess, it's NetworkOnMainThreadException. You need to offload network calls to a background thread.

– laalto
Nov 21 '18 at 14:32

|
show 1 more comment

1

What's the specific problem

– fedache
Nov 20 '18 at 21:31

Next time, provide the error message you receive... stackoverflow.com/help/how-to-ask

– TallTed
Nov 20 '18 at 23:05

The specific problem is that I do not receive any response from server and the app crashes after installation. LogCat shows that the problem begins in this command: ResultSet resultSet = qe.execSelect();

– A Damian
Nov 21 '18 at 9:20

Please edit your question to include the "specific problem" details. Note that the sparqlEndpointUri for DBpedia is https://dbpedia.org/sparql (not https://dbpedia.org), and this must be reflected in your code.

– TallTed
Nov 21 '18 at 14:31

If there's a crash, there's usually a crash stacktrace you should include here. If I'd have to guess, it's NetworkOnMainThreadException. You need to offload network calls to a background thread.

– laalto
Nov 21 '18 at 14:32

What's the specific problem

– fedache
Nov 20 '18 at 21:31

Next time, provide the error message you receive... stackoverflow.com/help/how-to-ask

– TallTed
Nov 20 '18 at 23:05

The specific problem is that I do not receive any response from server and the app crashes after installation. LogCat shows that the problem begins in this command: ResultSet resultSet = qe.execSelect();

– A Damian
Nov 21 '18 at 9:20

Please edit your question to include the "specific problem" details. Note that the sparqlEndpointUri for DBpedia is https://dbpedia.org/sparql (not https://dbpedia.org), and this must be reflected in your code.

– TallTed
Nov 21 '18 at 14:31

If there's a crash, there's usually a crash stacktrace you should include here. If I'd have to guess, it's NetworkOnMainThreadException. You need to offload network calls to a background thread.

– laalto
Nov 21 '18 at 14:32

|
show 1 more comment

1 Answer
1

active

oldest

votes

This --

    String sparqlEndpointUri = "https://dbpedia.org";

-- should be this --

    String sparqlEndpointUri = "https://dbpedia.org/sparql";

answered Nov 20 '18 at 23:04

TallTed

6,14321527

I tried this but still is not working. However, thanks for the interest.

– A Damian
Nov 21 '18 at 9:29

1

@ADamian "not working" is not helpful... what does not work? errors, empty result, etc?

– AKSW
Nov 22 '18 at 4:03

add a comment |

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1 Answer
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active

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1 Answer
1

active

oldest

votes

This --

    String sparqlEndpointUri = "https://dbpedia.org";

-- should be this --

    String sparqlEndpointUri = "https://dbpedia.org/sparql";

answered Nov 20 '18 at 23:04

TallTed

6,14321527

I tried this but still is not working. However, thanks for the interest.

– A Damian
Nov 21 '18 at 9:29

1

@ADamian "not working" is not helpful... what does not work? errors, empty result, etc?

– AKSW
Nov 22 '18 at 4:03

add a comment |

This --

    String sparqlEndpointUri = "https://dbpedia.org";

-- should be this --

    String sparqlEndpointUri = "https://dbpedia.org/sparql";

answered Nov 20 '18 at 23:04

TallTed

6,14321527

I tried this but still is not working. However, thanks for the interest.

– A Damian
Nov 21 '18 at 9:29

1

@ADamian "not working" is not helpful... what does not work? errors, empty result, etc?

– AKSW
Nov 22 '18 at 4:03

add a comment |

This --

    String sparqlEndpointUri = "https://dbpedia.org";

-- should be this --

    String sparqlEndpointUri = "https://dbpedia.org/sparql";

answered Nov 20 '18 at 23:04

TallTed

6,14321527

This --

    String sparqlEndpointUri = "https://dbpedia.org";

-- should be this --

    String sparqlEndpointUri = "https://dbpedia.org/sparql";

answered Nov 20 '18 at 23:04

TallTed

6,14321527

answered Nov 20 '18 at 23:04

TallTed

6,14321527

answered Nov 20 '18 at 23:04

TallTed

6,14321527

answered Nov 20 '18 at 23:04

TallTed

6,14321527

I tried this but still is not working. However, thanks for the interest.

– A Damian
Nov 21 '18 at 9:29

1

@ADamian "not working" is not helpful... what does not work? errors, empty result, etc?

– AKSW
Nov 22 '18 at 4:03

add a comment |

I tried this but still is not working. However, thanks for the interest.

– A Damian
Nov 21 '18 at 9:29

1

@ADamian "not working" is not helpful... what does not work? errors, empty result, etc?

– AKSW
Nov 22 '18 at 4:03

I tried this but still is not working. However, thanks for the interest.

– A Damian
Nov 21 '18 at 9:29

@ADamian "not working" is not helpful... what does not work? errors, empty result, etc?

– AKSW
Nov 22 '18 at 4:03

add a comment |

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